Computer, storage, and networking technologies have made vast quantities of information readily available. Queries can be used to limit the amount of information to be viewed for a particular purpose. For example, one might want to select, from a database of automobile accident records, accidents involving a particular brand and model of automobile and in which an airbag deployed. To this end, one can define a query specifying the brand and model and the condition that deployment of an airbag was reported. A database engine could return all accident records meeting the query pattern. Analysis could then be applied to the subset of automobile accident records of interest, which might be a small subset of the automobile accident records of interest.